E. coli Infections

Question 1

E. coli: General characteristics

Answer 1

• G-neg bacillus
• many strains are motile (peritrichous flagella)
• most common serotypes in poultry infections:
  
  • O2
  • O35
  • O78
• mainly described in chicken, turkey, and duck…can and does infect all avian spp.

Question 2

Diseases/conditions caused by E. coli in avian spp.

Answer 2

• embryonic and chick mortality
• coli septicemia
• air sac disease
• salpingitis (distention of oviduct d/t inflammatory exudate in the lumen)
• peritonitis
• panophthalmitis = eyes inflamed and chicks are blind
• synovitis
• pericarditis
• avian cellulitis = skin and underlying structures thick and discolored
• coli granuloma = Hjarre’s dz. = chronic phase of E. coli

Question 3

E. coli: Transmission

Answer 3

1. organisms in the GIT&raquo_space; shed in feces&raquo_space; contaminate egg shell and penetrate to yolk, or through oviduct&raquo_space; egg infected&raquo_space; embryo mortality (usually in late incubation)&raquo_space; infected hatch typically w/ early mortality
2. organisms in the GIT&raquo_space; shed in feces&raquo_space; causes heavy environmental contamination in poultry houses&raquo_space; infects chicks via respiratory and enteric routes&raquo_space; results in coli septicemia of enteric or respiratory (= air sac dz.) origin

Question 4

E. coli: Lesions

Answer 4

• lesions in embryos and dead chicks up to 3 wks old
• lesions similar to those seen in paratyphoid infections
• i.e. omphalitis (“Navel ill”/”Mushy Chick Disease”) = inflammation/infection/congestion of yolk sac = not absorbed by chick&raquo_space; coelomic cavity greatly distended +/- peritonitis and umbilicus infected and remains open
• lesions of peritonitis more common in 1-3 wk old chicks
• hemorrhagic liver and spleen with pinpoint necrotic foci
• pericarditis
• congested kidneys

Question 5

E. coli: Clinical signs

Answer 5

• depressed chicks with drooped head
• chicks huddled near heat source
• edema and yellow-green discoloration of sternal SQ = b/c chicks tend to lay in sternal recumbency&raquo_space; pressure on sternum causes this edema and discoloration
• mortality in chicks seen from hatching up to ~2 wks old
• reduced weight gain in chicks surviving after 3 weeks

Question 6

E. coli: Coli septicemia - Enteric origin

Answer 6

• acute septicemic infection
• more common in turkeys
• E. coli enters blood via intestinal mucosa damaged by infectious agents
• high mortality = >30-40%
• swollen liver with pinpoint necrotic foci
• fibrinous pericarditis
• congested muscles
• can become complicated infection, i.e. w/ mycoplasma

Question 7

E. coli: Coli septicemia - Respiratory origin

Answer 7

• causes air saculitis = air sacs thick and cloudy with caseous exudate
• most common type of coli septicemia
• enters blood via damage to respiratory mucosa by infectious and/or non-infectious agents such as:
  
  • IBV (avian infectious bronchitis)
  • NDV (Newcastle disease virus)
  • mycoplasma
  • ammonia
• high morb., low mort. (10-20%)
• perihepititis = liver is dark and swollen
• chronic pericarditis
• birds emaciated with poor carcass quality

Question 8

E. coli: Dx, DDx, and Tx

Answer 8

• Dx = isolation and ID (culture)
• DDx = omphalitis caused by other agents, acute septicemia (salmonella, fowl cholera)
• Tx = abx…freq. develops resistance = need C&S!

Question 9

E. coli: Px and Control

Answer 9

• as for paratyphoid infection:
  
  • egg sanitation and fumigation
  • hatchery hygiene
• raise mycoplasma-free birds
• good husbandry methods
• vaccines (trying inactivated and live - provides protection against homologous serotypes)